A spittlebug of the genus Aphrophora Germar, 1821 (Hemiptera: Cercopoidea: Aphrophoridae) occurs in profusion on many coastal California populations of invasive exotic iceplant, Carpobrotus edulis (L.) N. E. Brown (Aizoaceae), a spreading, mat-forming, perennial succulent. Described here as Aphrophora moscoviciae sp. nov., it occurs along the Pacific Coast and San Francisco Bay, from Marin County south to at least Ventura County, and achieves remarkably high population levels in some localities, with a maximum density of 2700 nymphs/m², an apparent world record for spittlebugs. While it appears to be endemic to California, native hosts are unknown. It shares habitats with three demonstrated spittlebug vectors of the plant pathogen Xylella fastidiosa Wells et al. (Xanthomonadaceae), including one, Philaenus spumarius (Linnaeus, 1758), that is common on iceplant. This suggests that it could play a role in broader transmission networks among cultivated and wild plants.